The invention relates to apparatus for metering and dispensing flowable materials, and more particularly to improvements in apparatus for admitting metered quantities of one or more flowable additives to a stream of water or another liquid.
It is known to equip a metering apparatus with a cylinder which receives a flowable additive from a vessel and contains a piston which is used to expel additive from the cylinder into a conduit for a stream of a hydraulic fluid. The channel which connects the vessel with the cylinder is sealed when the transfer of a selected quantity of additive into the cylinder is completed and remains sealed thereafter prior to renewed actuation of the piston to expel additive from the cylinder.
Metering apparatus of the above outlined character are used for admission of an additive (e.g., a comminuted solid, liquid or gaseous disinfectant, an alkaline cleaning solution or an acid) into tap water or another cleaning fluid which is to be conveyed through one or more pipelines for beer or other beverages. Apparatus which can be used to clean pipelines in restaurants, bars and/or other beverage dispensing establishments normally employ shuttle valves of the type disclosed, for example, in commonly owned U.S. Pat. Nos. 4,607,410 and 4,955,100. The disclosures of these patents are incorporated herein by reference. In many instances, the cleaning liquid is tap water which is admitted into the shuttle valve for repeated circulation through one or more pipelines which require cleaning. Spent tap water is discharged through an outlet of the shuttle valve. The effectiveness of tap water as a cleaning agent can be greatly enhanced if the water is mixed with a metered quantity of a suitable soluble or insoluble additive, e.g., a detergent, a disinfectant or any other substance which can but need not be partly or fully dissolved in tap water and is conveyed through the pipeline or pipelines prior to leaving the cleaning apparatus by way of the outlet of the shuttle valve.
An apparatus which can be used to admit metered quantities of a suitable additive to tap water or another cleaning liquid is described and shown in commonly owned published German patent application No. 33 20 293 A 1. The metering apparatus is combined with a cleaning apparatus which can be of the type described in U.S. Pat. No. 4,607,410, and the metering apparatus comprises a stationary vessel which contains a supply of flowable additive and is installed at a level above a stationary metering cylinder. A flow regulating valve is provided to admit additive from the vessel into the cylinder, and such additive is expelled from the cylinder by a reciprocable piston to be admitted into a conduit which conveys a stream of cleaning liquid to the inlet of the shuttle valve. A drawback of the metering apparatus which is described in the published German patent application is that, if the seat and/or the valving element of the flow regulating valve between the vessel and the cylinder is contaminated, the cylinder continuously receives a trickle or a larger flow of additive so that the percentage of additive in the cleaning liquid rises above an optimum or permissible value. The German patent application does not describe and/or show any controls for the flow regulating valve between the vessel and the cylinder. The vessel must be refilled from time to time with attendant danger of admission of contaminants into the supply of additive therein. Furthermore, refilling of the vessel is a dangerous undertaking if the additive is a strongly acidic, caustic or other aggressive substance. It has been found that the just described metering apparatus is incapable of invariably ensuring the admission of accurately metered additives and that the degree of automation of the additive admitting operation is insufficient.
U.S. Pat. No. 4,823,818 to De Buyer discloses a dispensing device for washing products. The patented device includes manually operated means for injecting a given quantity of washing products into the container of a dishwasher at the start of a washing operation. A regulating device is provided to admit washing products during a washing cycle; such regulating device is activated in response to closing of a door or cover for the container of the dishwasher.
Published German patent application No. 26 11 493 A 1 of Provera GmbH discloses a liquid metering apparatus wherein the piston of a cylinder and piston unit is biased to one end position by a spring in order to draw a metered quantity of a liquid from a vessel. A hydraulic fluid is used to move the piston in the opposite direction so that the fluid-propelled piston expels the metered quantity of liquid into a consumer.
Commonly owned published German patent application No. 33 47 003 A1 describes a cleaning apparatus which employs a shuttle valve of the type described and shown in commonly owned U.S. Pat. No. 4,607,410. The shuttle valve forms part of a module which further comprises a pump and a motor as well as a storing facility for sponge-like cleaning elements.
Published European patent application No. 0 184 333 of Nystuen describes a volumetric gravity feed liquid dispenser which can be used in conjunction with a dishwashing rack to deliver a liquid detergent or in conjunction with a water closet to discharge a deoderant and/or cleaning liquid.
German-language pamphlet entitled "Reinigungsapparat `Fasil`" describes a cleaning apparatus which can be used in breweries and similar establishments. The pamphlet suggests to use a pump or a pressure regulator in order to clean pipes or hoses with a solvent.